Barack Obama, Michelle Obama join Stevie Wonder on stage at Baltimore tour stop

BALTIMORE -- Barack Obama, the nation's 44th president, and former First Lady Michelle Obama, joined legendary singer and songwriter Stevie Wonder on stage during his tour stop Tuesday at CFG Bank Arena in Baltimore .

Wonder is in the middle of his 10-city "Sing Your Song! As We Fix Our Nation's Broken Heart" tour before election day, encouraging people to vote.

Barack Obama, a Democrat, previously announced his endorsement for Vice President Kamala Harris in the presidential election. Last week, he surprised workers at a Kamala Harris campaign office in Pittsburgh.

Wonder also performed at the Democratic National Convention in August .

Wonder has won 25 Grammy Awards, was inducted into the Rock and Roll Hall of Fame and the Songwriters Hall of Fame. He won the Presidential Medal of Freedom and was a key figure in making Martin Luther King Jr.'s birthday a federal holiday.

He is known for many hits, including "I Just Called to Say I Love You," "I Wish," "Sir Duke," "Higher Ground," "Superstition" and "Isn't She Lovely," among others.